Let's Read the 4e Monster Manual/Vault: Bodak
A D&D original, the bodak first appeared in AD&D if I’m not mistaken. They were one of the many high-level undead that resulted when someone really evil died, with the specific type of evil generating different monsters. They’ve always looked like Grey aliens with oblong heads and narrow, empty eyes.
Here, they keep the look, but have a different origin: when a Nightwalker kills someone, it can ritually transform the slain creature’s corpse and spirit into a bodak servant. Therefore, bodaks can be found either hanging around nightwalkers, or running missions for their masters along with other undead.
Bodaks are Evil and not very smart, so the occasional free bodak is more likely to find itself a lair where it can ocasionally kill passers-by than to hatch complicated evil schemes of its own.
This Monster Manual entry gives us two different bodaks: the Skulk and the Reaver. There are no bodaks in the Monster Vault.
Bodak Skulk
From the looks of it, this is the classic model. A level 16 Lurker, with Int 6 and 124 HP, the skulk has darkvision and an Agonizing Gaze aura: anyone in its radius (5 squares) who makes a ranged or melee attack against the bodak takes 5 necrotic damage before the attack, and a -2 penalty to the roll. This is both a gaze and a fear effect, and doesn’t affect people doing close or area attacks, so wizards take note!
As expected, this is a Medium Shadow Humanoid (undead). This is not the first undead monster we see in this Let’s Read, but I haven’t explained the keyword before. It’s pretty much like you’d expect: undead don’t breathe or sleep, aren’t affected by anything that specifically targets living creatures and are affected by anything that targets undead.
The Skulk moves at speed 6. It’s immune to disease and poison, and has Resist 15 necrotic. It’s also Vulnerable 5 to radiant damage, and if it takes radiant damage it can’t weaken anyone with its basic attack for a turn.
The Bodak Skulk attacks with a slam that does a mix of physical and necrotic damage, and also weakens the target for a turn. Once per encounter it can focus its gaze on a single target, attacking their Fortitude: if this hits a weakened PC, the PC is immediately reduced to 0 HP. This is pretty serious, but it’s not quite instant death like in previous editions. If the target is not weakened, they take necrotic damage and lose a healing surge (this edition’s equivalent of negative levels).
Finally, as an at-will standard action, the creature can turn invisible, insubstantial and gain phasing. In this state it can do nothing but move, and can return to physicality as a free action.
This thing is going to follow the party invisibly while waiting for a chance to attack, then will reveal itself right next to a vulnerable character, weaken then with the slam and fix its gaze on them on its next turn. It will likely do all of this as the party is hit by a group of less subtle undead.
The skulk’s big Lurker Attack is the death gaze - once that’s expended, it becomes a somewhat more fragile skirmisher. Early edition damage issues make it quite weak in direct combat, and fixing those would go a long way to make as threatening as its level indicates.
Bodak Reaver
The Bodak Reaver is the Skulk’s smarter, braver cousin. Another Medium Shadow Humanoid (undead), the reaver is a Level 18 Soldier with Int 10 and 175 HP, wearing plate and wielding a greataxe.
It has pretty much the same resistances and vulnerabilities as the Bodak Skulk, except its necrotic resistance is a little higher at 20. Its basic greataxe attack does a mix of physical and necrotic damage, and both dazes and weakens on a hit. Since the text of the vulnerability is the same, I’m going to assume this still dazes even when it can’t weaken, and that this is the main way in which it fulfills its soldierly function.
The Reaver’s Agonizing and Death Gazes are the same as the skulk’s. Bodaks gonna bodak.
Finally, the reaver is a Death Drinker: if any living creature is reduced to 0 hit points within 5 squares of it, the reaver gains +1 to attacks for a turn, and 15 temporary HP. That’s not just PCs! If the reaver has living allies, their deaths will also make it stronger.
Like the skulk, the Bodak Reaver is in major need of a damage update. Other than that I don’t see anything wrong with it.
Encounters and Final Impressions
The suggested encounter here is level 18, a bodak reaver and two slaugher wights commanded by a cambion hellfire magus.
Overall, it seems 4e Bodaks aren’t going to fill a party with dread in the same way an old-school bodak would, since each of them can only mostly kill someone with a gaze once per fight. Of course, an all-bodak monster squad can still potentially kill the whole party with their gazes if they coordinate well, something which is already perfectly possible at Int 10.
Making custom bodaks is doable: aside from being undead, their signature abilities are the Agonizing and Death gazes, and a melee attack that weakens. A memorable villain the party has faced in the past could be raised as a bodak and employed as a lieutenant by a necromancy-themed Big Bad.